Multimedia Broadcast Multicast Services (MBMS) is a point-to-multipoint interface specification for existing and upcoming wireless networks. For broadcast transmission across multiple cells, MBMS defines transmission via single-frequency network configurations. Multicast-Broadcast Single Frequency Network (MBSFN) is a communication channel defined in Long Term Evolution (LTE), the fourth-generation (4G) cellular networking standard. MBSFN includes a plurality of cells combined to a single frequency with the cells all transmitting the same data. Logically MBSFN makes different cell antennas appear as a single cell antenna with a large coverage area. From a radio's perspective, it is combining signals from what appears as a single cell, but with some delay spread. One exemplary application for MBMS and/or MBSFN is public safety applications such as using Push-to-Talk (PTT) for public safety responders.
In various PTT applications, there can be various user equipment (UEs) that participate in PTT calls outside their associated home server. For example, multiple user equipment (UE) can be on a scene of an incident or the like with some UEs being from different PTT server areas. As such, various conventional network-network interface (NNI) techniques have been developed between servers for handling PTT services. An exemplary NNI is the Open Mobile Alliance (OMA) Push to talk Over Cellular V2.1 (August, 2011), the contents of which are incorporated by reference herein. Another exemplary NNI is the Project 25 Inter-RF Subsystem Interface Protocol(s) (ISSI) defined in TIA-102.BACA-A (January 2009), the contents of which are incorporated by reference herein.
Disadvantageously, in current systems and methods, a controlling server is aware of all its group members, however, it can only manage resources for members homed at the controlling server. The controlling server does not know about visiting UEs that belong to participating server(s), therefore it cannot consider them when making decision on utilizing or not MBMS service in each of the MBSFN areas. On the other hand, a participating server does not know whether it's UEs which are visiting the controlling server's area will be able to receive voice via MBMS in the area or whether they need voice to be delivered to them via uncast bearer. It would be advantageous for a controlling server to have information regarding how many UEs are in an area for possibly allocating MBMS resources in a given MBSFN area for a call.
Accordingly, there is a need for systems and methods for enhanced Push to Talk (PTT) Network-Network Interface (NNI) systems and methods for Multimedia Broadcast Multicast Services (MBMS).
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.